1. Field of the Invention
The present invention relates to a communication apparatus that communicates data with an external device on a frame-by-frame basis, and to a control method thereof.
2. Description of the Related Art
At present, connecting a display device such as a digital television (DTV) to a recording device such as a hard disk recorder (HDR) and transmitting video data, audio data, and the like (referred to collectively as “AV data” hereinafter) stored in the recording device to the display device is commonly carried out. HDMI (High-Definition Multimedia Interface) is known as a digital interface for connecting recording devices with display devices. Meanwhile, DVI (Digital Visual Interface) is known as a digital interface for connecting PCs (Personal Computers) with display devices. With interfaces such as DVI and HDMI, video data is communicated on a frame-by-frame basis. However, DVI supports only the communication of video data; with DVI, the communication of audio data is not supported.
Devices that combine a recording device with a playback device in a single package, such as a DTV equipped with HDR functionality (an HDR-equipped DTV), are becoming widespread. It is preferable for an HDR-equipped DTV to have functionality for receiving video data from other recording devices and sending video data to other display devices, or in other words, to have functionality for bi-directional communication of video data.
However, interfaces such as DVI and HDMI are only capable of sending video data in a single direction. Furthermore, like video data, HDMI can only send audio data in a single direction. For this reason, with the DVI and HDMI interfaces, it has been necessary to utilize two of such interfaces in order to realize bi-directional communication of video data or AV data comprising video data and audio data.
A technique for performing bi-directional data communication using blanking intervals (see Japanese Patent Laid-Open No. 2001-136509) is known as a response to this problem. Furthermore, configuring analog V and A cables to be capable of bi-directional transmission, adding a control signal line, and implementing this structure in a single connector to be used as a cable for connecting a backup VTR is also known (see Japanese Patent Laid-Open No. 2000-83209).
However, Japanese Patent Laid-Open No. 2001-136509 does not disclose switching the transmission direction of data in periods aside from the blanking intervals.
Moreover, Japanese Patent Laid-Open No. 2000-83209 discloses neither a specific configuration for switching the transmission direction nor the sequence through which the switch is carried out.
In other words, with Japanese Patent Laid-Open No. 2001-136509 and Japanese Patent Laid-Open No. 2000-83209, it is not possible to switch the transmission direction of data in a communication apparatus that communicates data on a frame-by-frame basis (this typically refers to video data, but is not limited thereto).